refined some copying behavior of Monomer- and ComplexPatterns
refined some copying behavior of Monomer- and ComplexPatterns

* added MonomerPattern.__call__ to return a copy with updated site conditions
  (in the same vein as Monomer.__call__)
* removed MonomerPattern._copy as this functionality is now in __call__
* renamed ComplexPattern._copy to copy

d-fan/pysb,alubbock/pysb-legacy,spgarbet/pysb,alubbock/pysb,LoLab-VU/pysb,LoLab-VU/pysb,spgarbet/pysb,jmuhlich/pysb,neurord/pysb,pysb/pysb,neurord/pysb,alubbock/pysb-legacy,d-fan/pysb,johnbachman/pysb,d-fan/pysb,alubbock/pysb-legacy,neurord/pysb,spgarbet/pysb,alubbock/pysb-legacy,johnbachman/pysb